Seller kept horrible records

[Chris Seveney]

Found an off market multi family that a women wants to sell (she is elder and husband recently passed) The duplex has two tenants but she noted they have been on month to month for years. Told me what they pay but had no lease. Also she has no financial records as she gave discounts for paying cash etc. Is there any other way to analyze the deal ? Based on current market rates in the area it would cash flow $200/door after putting in 10% capex/PM/repairs (10% each) Should I be suspicious and is there a way to protect myself. I don't have accepted offer etc. Any advise appreciated Thanks